Volume 3, No. 2 Special section: High-Performance Seismic Systems edited by Prof. M. Nishiyama Damage Control of High-Rise Building with Energy Dissipation Devices (Invited paper) Nobuyuki Izumi, Takahiro Watabe and Hiroyuki Takenaka Journal of Advanced Concrete Technology, 3(2) 187-206, 2005 The paper presents that an energy dissipation device (damage fuse) in its reinforced concrete (RC) frame can upgrade the ability to dissipate the energy created by earthquake excitations. In case a damage fuse is applied to RC frame, it should be taken into consideration that the behavior such as cracking of attachment members and flexural yielding of reinforcing bars can reduce the effect of damage control. Therefore, the validity of performance evaluations of its frame with a damage fuse and analysis models should be thoroughly examined. It also presents that the analysis models of RC frame with a damage fuse effectively demonstrate the restoring force characteristics obtained from test results of horizontal loading. In addition, the paper states that several projects of high-rise RC buildings have already chosen a damage fuse in order to control serious damage to RC buildings subjected to strong earthquakes. Emerging Solutions for High Seismic Performance of Precast/Prestressed Concrete Buildings (Invited paper) Stefano Pampanin Journal of Advanced Concrete Technology, 3(2) 207-223, 2005 Major advances have been observed in the last decade in seismic engineering with further refinements of performance-based seismic design philosophies and definition of the corresponding compliance criteria. Following the worldwide recognized expectation and ideal aim to provide a modern society with high (seismic) performance structures able to sustain a design level earthquake with limited or negligible damage, emerging solutions have been developed for high-performance, still cost-effective, seismic resisting systems, based on adequate combination of traditional materials and available technology. In this paper, an overview of recent developments and on-going research on precast concrete buildings with jointed ductile connections, relying on the use of unbonded post-tensioned tendons with self-centering capabilities, is given. A critical discussion on conceptual behavior, design criteria and modeling aspects is carried out along with updates on current trends in major international seismic code provisions to incorporate these emerging systems. Examples of existing on site applications based on a recently developed cable-stayed and suspended solution for frame systems are provided as further confirmation of the easy constructability and speed of erection of the overall system.. Prediction of Response of Prestressed Concrete Buildings to Earthquake Excitation Using Capacity Spectrum Method Minehiro Nishiyama Journal of Advanced Concrete Technology, 3(2) 225-231, 2005 Non-linear time-history analyses on single-degree-of-freedom systems with load-displacement relations of prestressed and conventional reinforced concrete members are reported. The analytical results are used for investigating response characteristics of prestressed concrete systems and deriving substitute damping. Energy time-history of prestressed concrete system is compared with that of reinforced concrete. The substitute damping obtained is compared with equivalent viscous damping derived directly from load-displacement relationship of the systems. Referring to the substitute damping from the dynamic response analyses and the equivalent viscous damping from stationary load-displacement curves, an equivalent structural damping for concrete structures to be used in the capacity spectrum method is proposed.. Development and Realization of Base Isolation System for High-Rise Buildings Tsutomu Komuro, Yasuhiro Nishikawa, Yuichi Kimura and Yuji Isshiki Journal of Advanced Concrete Technology, 3(2) 233-239, 2005 The high-rise buildings with the base isolation system have been realized by studying the practical applicability of this system, that is, by extracting and resolving the several problems in the actual design. Sendai MT building is the first base-isolated building with over 60 m height in Japan, and Thousand Tower was the tallest base-isolated residential Tower in Japan when completed. With the base isolation system, it is possible for the high-rise buildings to possess not only the high seismic performance, but also the flexible planning in the design, using high strength materials and long span structure systems as well. The seismic data were obtained from the seismographs in Sendai MT building, when the Off -Miyagi earthquake occurred in May 26, 2003. These data show that the base isolation system acted effectively on the high-rise building. Modeling of Effective Diffusion Coefficient of Substances in Concrete Considering Spatial Properties of Composition Materials Yoshitaka Kato and Taketo Uomoto Journal of Advanced Concrete Technology, 3(2) 241-251, 2005 This research is conducted to develop a model to predict effective diffusion coefficients of substances in concrete considering with spatial properties of composition materials. In this model, concrete is assumed to be composed of cement paste, interfacial transition zone and aggregate. Proposed model can appropriately evaluate the effective diffusion coefficient of chloride ion in concrete in previous research. The influence of spatial properties of each composition material on the dispersion of the effective diffusion coefficient is analytically investigated. The influence of cement particle arrangement is larger than that of fine and coarse aggregate, and that influence becomes remarkable as W/C becomes low. Moreover, the influence of interfacial transition zone on the diffusion of chloride ion in concrete is also analyzed. It can be found that its influence is quite large, so that interfacial transition zone should be taken into account for simulating the diffusion in cementitious materials. Simulation of Coupled Corrosive Product Formation, Migration into Crack and Propagation in Reinforced Concrete Sections Kukrit Toongoenthong and Koichi Maekawa Journal of Advanced Concrete Technology, 3(2) 253-265, 2005 This paper aims to numerically simulate corrosion induced cracking and its propagation over a section of reinforced concrete members and the penetration of corrosive gel product into crack gaps is focused. A coupled steel core and surrounding corrosion product are mechanically represented by a fictitious growing composite, with which the corrosive cracking initiation and subsequent propagation are simulated by 2D nonlinear crack analysis. In the case where a corrosive crack stably propagates such as large cover and/or comparatively small diameter of steel, the injection of corrosive gels into evolving cracks becomes substantiated, and the coupled system of gel formation, migration and crack propagation is newly presented. The simulation scheme was verified through RC sections subjected to accelerated corrosion by electric charge with regard to crack patterns and critical corrosion rates when cracks reach the outer surface of members. Behevior of Confined High Strength Concrete Columns under Axial Compression Umesh K. Sharma, Pradeep Bhargava and S. K. Kaushik Journal of Advanced Concrete Technology, 3(2) 267-281, 2005 An experimental study was carried out to investigate the behavior of high strength concrete short columns confined by circular spirals and square ties under monotonically increasing concentric compression. The test variables included volumetric ratio, spacing and yield strength of transverse reinforcement, longitudinal reinforcement ratio, lateral steel configuration, shape of cross section and concrete compressive strength. The effects of these variables on the uniaxial behavior of high strength concrete columns are presented and discussed The results indicate that more confinement is required in columns of high strength concrete than in columns of low strength concrete to achieve the desired post-peak deformability. The behavior of high strength concrete columns is characterized by the sudden spalling of concrete cover, leading to a loss of axial capacity. A comparative study of existing confinement models of high strength concrete columns was also conducted to assess their capabilities of predicting the actual test behavior. To this end, the stress-strain curves of the specimens tested in the present study were compared with the ones predicted by the various models. It is shown that Legeron & Paultre (2003) model estimates the actual experimental curves more closely as compared to the other models employed in the study. Punching Shear Failure Mechanism of Open Sandwich Slab and its Parameters' Effects Ahmed Farghaly, Hitoshi Furuuchi and Tamon Ueda Journal of Advanced Concrete Technology, 3(2) 283-296, 2005 Effort has been given using 3D FEM program to predict the punching shear failure mechanism and its strength of open sandwich slabs with stud. In the analysis the stud is modeled by link element for shear transfer, whose constitutive model is derived from authors?experimental study, and truss element for tension transfer. The results show very good agreement between the analytical and experimental values. Punching shear failure phenomena is carefully examined in the analysis observing predicted concrete cracking and concrete crushing. Based on the analytical observation a quantitative study on factors, such as concrete strength, plate thickness, stud height, and stud spacing, has been done to develop analytical expression for computing the punching shear strength of open sandwich slab. 3D Nonlinear Punching Shear Simulation of Steel-Concrete Composite Slab Ryosuke Takahashi, Yasuhiko Sato, Katsuyuki Konno and Tamon Ueda Journal of Advanced Concrete Technology, 3(2) 297-307, 2005 To analyze punching shear behavior of steel-concrete composite slab accurately by 3D nonlinear finite element method, the interface between concrete and steel plate has to be modeled precisely. In this study, the interface model is developed based on relationship between shear force and relative displacement of stud observed in a loading test of steel-concrete composite beams. And the result of taller stud is improved considering shear-reinforcing effect by the smeared reinforced concrete mode. Failure characteristic and stress state are also agreed with test result and it can be said that the model and method used in this study is reasonable and can simulate punching shear failure of composite slab almost. However, the problem remains in the thick diameter case and more experiments and further investigation are needed to make the simulation more accurate. Prediction of Behavior and Shear Strength of Reinforced Concrete Beams Using Nonlinear Strut-Tie Model Approach Young Mook Yun and Chang-Geun Cho Journal of Advanced Concrete Technology, 3(2) 309-319, 2005 Numerous analytical techniques, analytical theories, and analytical/design models have been proposed for the rational shear designs and shear behavior examinations of reinforced concrete beams. However, since shear design regulations in design codes are primarily based on experimental observations along with the elastic beam theory, the regulations may not accurately represent the true shear behavior of general reinforced concrete beams. Accordingly, much attention has been focused on the development of a general and consistent model or method. In this study, the strength and behavior of four reinforced concrete beams tested to shear failure were estimated using a nonlinear strut-tie model approach. Based on the strut-tie model analysis results, the validity of the nonlinear strut-tie model approach in the reasonable design of reinforced concrete beams and in the accurate examination of many shear-related failure phenomena was evaluated. Beam-column Joint with Steel Fiber Reinforced Cementitious Composite in Steel Structures Yoshio Kaneko, Hirozo Mihashi and Kazuki Kirikoshi Journal of Advanced Concrete Technology, 3(2) 321-330, 2005 In this paper, the structural performance of steel structures employing a beam-column joint system with steel fiber reinforced cementitious composites is experimentally examined. The beam-column joint is achieved by filling steel fiber reinforced cementitious composites into the gap between a U-section bracket and a middle beam. In the test, simple beam specimens are employed and the cyclic shear load is applied, focusing on the required bracket-length, the effect of fiber reinforcement and the influence of loading hysteresis. The experimental results show that the specimens with steel fiber reinforced cementitious composites give sufficient strength and ductility without prominent damage in comparison to the specimens with high strength mortar and conventional concrete.